Land use evolution can be considered as a very useful indicator to evaluate desertification risk since human activities are, together with climatic conditions, the two main factors responsible for desertification. Inappropriate land uses are unsustainable, and bad management of resources leads to land degradation and desertification.

This indicator can help us to know which are the traditional uses and the suitability of the soil to accommodate other potential uses. It also shows if the land use is changing from a sustainable use to a more unsustainable use. This sustainability can be determined mainly by the relationship between the soil conditions and the change made in the type of use, including the cultivation techniques. Traditionally, the use of the soils was based on their natural characteristics (soil quality, slope, etc.) and the availability of water (that, from a climatic point of view, also defined the suitability of land uses in specific areas) so the land use could be an indicator of the soil characteristics. Now it is more complicated since new cultivation techniques and infrastructures make economic issues (irrigation farming is much more profitable than dry farming or pastures) the main driving force for the change in land use. For that reason it is necessary to know the evolution of the land uses in one area to detect the change in land uses and to prevent degradation processes.

Land use evolution is the history of the different land uses taking place in one area. It shows the uses, cultivations and techniques that have taken place in one area, and those aspects, together with climatic conditions, have made initial soil and vegetation characteristics evolve to present conditions. This is very important in Mediterranean countries since in these areas soils have very specific aptitudes and clear and sensitive responses (in terms of sustainability) for different uses. Dry farming, irrigation farming and pastures (apart from forest lands) are the main sustainable uses and techniques. Traditionally, irrigation farming had been placed in the more fertile lands while dry farming or pastures uses were located in less fertile land or where irrigation was not possible. The change in agriculture prices, as well as socio-economic changes (abandonment of agriculture, migration to urban areas, etc.) has forced these activities to become a marginal use of land, persisting only in areas where no other use is possible. Farmers are prevented from investing in conservation measures because of the low profitability of this kind of farming. Moreover, the steady increase in the difference of incomes between irrigation farming and dry farming (or pastures) and the new technological developments (both new irrigation and transport infrastructures and irrigation and cultivation techniques) make it possible and profitable to place irrigation farming in new areas (traditionally dry farming areas) with greater benefits, especially if fast ways of transporting products to European markets are available. In both cases more pressure is put on soils and specifically in traditionally dry farming/pasture lands this pressure can lead to degradation since soils are not suitable for non-traditional development. The evolution of land uses in one area will show the risk of development of degradation processes that can result in desertification processes. The changes from sustainable uses to more intensive uses steadily puts pressure on the soil (considered as a resource), initiating or enhancing land degradation processes and often resulting in land abandonment.

It is possible to use, as benchmarks, some changes in land uses, describing them as land uses moving from more sustainable to less sustainable or, from less sustainable to more sustainable (always in terms of risk of erosion and degradation processes)

X means that the change made is increasing the risk or rate of degradation processes.
O means that the change is not adding risk or increasing the rate of degradation processes.

In both cases it is necessary to assess not only the change but also the techniques used, the land management practices and the soil and climatic conditions. Only by incorporating these aspects in the assessment can it be considered a useful indicator. For that reason, in the Table it is possible to find, for the same land use change, both values.

From this Table, the ranges of values should be the number of Ha/time units (years-decades) of land that change to a more unsustainable use (as defined in the Table). There is no benchmark for the number of Ha for land use changes; it is just that land use changes may be considered as increasing the risk of land degradation for the area and surrounding areas.

Brandt, J. & Thornes, J.B. (1996, eds.) Mediterranean Desertification & Land Use, Wiley, Chichester.

UNCCD Northern Mediterranean meetings. Workshop on desertification and land use in the Mediterranean basin 28-30 June 1993, Almeria, Spain.

World bank, 1995: Land Quality indicators.

D. J. Greenland and I. Szabolcs (Editors), 1994: Soil Resilience and Sustainable Land Use. Oxford University Press.

M. Marathianou, C. Kosmas, St. Gerontidis and V. Detsis, 2000: Land-use evolution and degradation in lesvos (Greece): a historical approach; Land degradation & development. 11: 63-73